1. Field of the Invention
Embodiments of the invention generally relate to an implantable heart therapy device having a therapy control unit that includes a tachycardia identification unit. The heart therapy device also includes a right-ventricular stimulation unit and a left-ventricular stimulation unit, wherein both the right-ventricular stimulation unit and the left-ventricular stimulation unit are connected to the therapy control unit. The therapy control unit triggers antitachycardia stimulation (ATP).
2. Description of the Related Art
European Patent 1 857 140 to Doerr et al., entitled “Heart Stimulator”, discloses a heart therapy device having a stimulation unit that is connected or can be connected to a stimulation electrode in order to stimulate a ventricle of a heart. The stimulation unit, of Doerr et al., may generate both stimulation pulses and defibrillation shocks, and may include at least one high-voltage capacitor, in which the electrical energy necessary for a defibrillation shock is stored.
Generally, heart therapy devices may include a detector that processes physiological signals received from the heart and, on the basis thereof, detects the presence of an acute ventricular tachycardia or fibrillation. Typically, heart therapy devices may also include a control unit connected to the detector and the stimulation unit, wherein the control unit is responsive to an output signal of the detector to control the stimulation unit to deliver a sequence of stimulation pulses or to deliver a defibrillation shock forming an antitachycardia therapy. The heart therapy device of Doerr et al. enables therapy delivery to a right ventricle of the heart.
Generally, heart therapy devices may be referred to as implantable cardioverter-defibrillators (ICD). Typically, heart therapy devices referred to herein are primarily implantable heart therapy devices that are able to treat tachycardia of the heart.
Generally, the term “tachycardias” includes both tachycardias represented by a stable heartbeat with pathologically high frequency, and also fibrillations. Therapies delivered by a heart stimulator, generally, include an antitachycardia stimulation or a defibrillation shock.
A defibrillation shock is typically an electrical pulse delivered to the heart and has sufficiently high voltage and energy to fully excite a heart chamber affected by fibrillation to therefore make the heart chamber refractory. Therefore, re-entrant excitation pulses, typical for fibrillations, are interrupted. In the case of tachycardia wherein a ventricle is affected, the tachycardia is often also referred to as ventricular tachycardia and is abbreviated by VT (in contrast to ventricular fibrillation VF). Generally, successful therapy is often possible using antitachycardia stimulation (antitachyarrhythmia pacing: ATP). Generally, with antitachycardia stimulation, the heart stimulator outputs a sequence of stimulation pulses, of which the energy is significantly lower than the energy of a defibrillation shock and which are not painful. Typically, with antitachycardia stimulation, such stimulation pulses of comparatively low energy are delivered with a frequency that is greater than the frequency of the determined tachycardia. Generally, tachycardia may be stopped in this way without a patient suffering from pain or without the energy demand being particularly high.
Typical therapy devices generally deliver stimulation pulses to one or both ventricles of a heart, to the left ventricle (LV) and/or to the right ventricle (RV). Such therapy devices are generally referred to as biventricular therapy devices.
Generally, previous ICD systems available on the market may operate exclusively with a right-ventricular VT/VF identification channel for the tachycardia identification and for the corresponding therapy selection. Typically, the stimulation location of the ATP may be programmed statically (RV, LV, BiV).
Generally, ICD systems may also provide, in the VF zone, an ATP therapy attempt, which is delivered immediately before or with the onset of charging, but only when the right-ventricular rhythm meets a frequency and/or stability criterion at the same time; such as an ATP one shot.
Typically, purely right-ventricular sensing used with current ICD systems may have the disadvantage that, in the event of dissimilar ventricular tachyarrhythmia, an incorrect therapy may be selected. If, for example, the rhythm in the right ventricle is already in a VF zone and is unstable, but the left ventricle is still stable, generally, the selection of a defibrillation shock is preferred over an ATP, although clinical observations show that an ATP delivery, for example in the left ventricle, may have a higher therapy success rate.
Generally, a further disadvantage of current systems includes the exclusive use of right-ventricular sensing for synchronization of a left-ventricular ATP. Typically, the exclusive use of right-ventricular sensing may be the reason why no clinical studies are known that demonstrate an advantage of left-ventricular ATP.
Generally, one-time ATP attempts in the VF zone do not take into account the left-ventricular rhythm and also do not take into account potential rhythm regularization during the charging time, and therefore potentially effective ATP attempts are not delivered.